Apparatus for cutting artificial filaments into short lengths



Dec. 29, 1953 R. H. SPEAKMAN 2,664,160

APPARATUS FOR CUTTING ARTIFICIAL FILMENTS INTO SHORT LENGTHS Filed June 27, 1951 2 Sheets-Sheet 1 Elli!!! INVENTOR.

Rqymond Jfigldenb 'bpakmm ATTORNEYS.

Dec. 29, 1953 R. H. SPEAKMAN 2,664,160

APPARATUS FOR CUTTING ARTIFICIAL FILMENTS INTO SHORT LENGTHS Filed June 27, 1951 2 Sheets-Sheet 2 INVENTOR RqymondJIpJden @npalmaq W M W ATTORNEYS.

Patented Dec. 29, 1953 APPARATUS FOR CUTTING ARTIFICIAL FILAMENTS SHORT LENGTHS Raymond Holden Speakman, Wheathamp stead, E g a d, s gner 10 Imperial Chem a Indus ri s limited; M llbcn n land Application June'27, 1951, Serial'No. 233,777

Claims priority, applicationGreat Britain July 10, 1950 5 Claims. (01. 164+61) This invention relates to an improved process for cutting continuous artificial filamentsinto short lengths. More particularly it relates to the production of staple fibre by cutting artificial filaments.

Many methods of cutting continuousartificial filaments into short lengths are known. I have found, however, that some artificial filament forming material such as synthetic linear polyamides, e. g. polyhexamethylene adipamide, and synthetic linear polyesters, e. g. polyethylene terephthalate yield filaments which are so tough that dililculty' is experienced in cutting them using known methods.

I have now found that such filaments can be cut more easily when the cutting edge of a knife blade is drawn across them rather than when the knife blade hits them for example, with a chopping action.

According to the present invention, there is provided'a process for cutting continuous filaments into short lengths wherein the continuous filaments are held in contact with a number of projections on a moving support so that they bridge the spaces between the proje-ctionsand are cut by at least one knife -blade mounted so that its edge can press against the filaments and s that e d nced it t n e ge I om an axis about which the blade rotates-varies along its l n th; the r t ti n of e blad in s nchronized with the movement of the moving support so that the blade makes contact with the filaments while they are bridging a Space between two projections but does not make contact with them when they are supported on a projection the point of contact'moving in the direction of movement of the filaments during the passage of the blade through the filaments. It is preferred that the blade is so shaped that; during its contact with the filaments, its point of contact penetrates, as the blade rotates, to a progressively greater degree into the space between twoadjoining projections. In this Way, he pressure of the blade upon the filament is maintained during the period of contact betweenthern. It is also preferred that the leading edge or the blade is curved so that pressure from the-cutting edge is rapidly brought to bearupon the filament but the leading edge of the blade does notstrike the ma-- ment.

In a preferred form of the inventionthe knife blade is bent so that the distance of the cutting edge from the axis of rotation varies progressively along its length, for example; it maybe bent so that it has the shape of a portion of an 2 Archimedes spiral. It will be apparent that in practice it is possible to work with blades which have simpler shapes. For example, a half circular blade can be mounted slightly off centreto obtain the required effect. The bend of the blade is intended to cause the cutting edgeto maintain contact with the filament for a time while' the knife slices through, i. e. the knife does not cut by virtue of a quick chop but by means of a -continuous pressure while the cutting edge slides across the filaments. 'The'shape of the blade enables it to maintain contact at the cutting point while the filaments are moving and the knife is cutting through the filaments.

The shape of the tuft of short lengths can be varied by varying the shape of the knives. When one knife is used, or when two knives of the same shape are mounted in the same way, all thecut lengths will be the same and the tuft will, in section, have the shape of a parallelogram.- Using two knives of-different shape, arranged to cut the filaments alternately, a tuft may be obtained which will be a trapezium inse'ction. This means that all the lengthsin thetuft will not be the same. For ease of cutting it is preferred that the movement of the point 'of contact of the cutting edge of the knife with the filament should move at exactly the same speed as the filaments. This is not essential however and cannot in fact take place when knives of different shapes are used.

Referring now to the accompanyin drawings which show, byway of example,- one' method of putting the invention into effect in an apparatus where a continuous filament tow is out intostaple fibre.

Fig.1 is a diagrammatic side elevation of the apparatus. n

Fig; 2 is a diagrammatic end elevation of the apparatus.

Fig. 3 is a diagrammatic vertical plan of theapparatus. I

Fig. 4 shows one knife blade'before it is shaped.

Figs. 1 and '2 showthe general operation of-the cutting process but do not show themet-hod for holding the filaments while they'are'being cut. Fig. 3 shows the method of holding the filarnents.

A wheel I having a groove I0 round its cireumference' has also radial spaces Z'positioned evenly round the wheel. This wheel is adapted to be rotated in the direction indicated round the axis 3. Continuous filaments 4 are fed into the circ'umferential' groove and are held firmly in this groove by a wheel I I which rotates about an axis I2 at an angle to the axis 3, and which has spring steel fingers l3 on its perimeter, which are positioned to lie in shallow grooves 5 when in contact with the wheel so that the filaments are held firmly just before, during and just after the filaments are cut, and when not in contact with the wheel are spaced therefrom to allow the continuous filaments to be fed to and the staple fibres to fall away from the apparatus. Two semicircular tapered knife blades 6 and 1 (one of which is shown in Fig. 4 before mounting) are mounted on a former 8 as shown. The edge ll of the blade is sharpened from point X to point Y and the leading edge of the blade [5 is rounded so that the blade leads into the space between the projections without catching or snagging the filaments and without a slashing action. The general shape of the blade is tapered so that it feeds gradually into the space and cuts all the filaments by a sliding action. The blade which is made of flexible steel is mounted on the former 8, of the required shape, by means of studs through the holes l6, and can thus be quickly and easily removed and replaced. The former is rotated about an axis 9 at such a speed relative to the speed of the wheel I that while the space shown at position a is moving to position b, the knife blade 6 has rotated so that the whole length of the blade has passed through the space and emerges from it when the space is in position b. The next space will then be in position a and the thin end of the blade 1 will enter the space.

If desired some preliminary shaping may be imparted to the blade to minimise stresses during bending when mounting it on the former. The blade may be strengthened by having some portions thicker than others, i. e. the strip of steel need not necessarily be of rectangular section.

It will be appreciated that any number of knives may be used as long as they are arranged to synchronise with the spaces.

For ease of operation it is preferred that the blade should be tapered. Thus that portion of the blade which first contacts the filaments must be narrower than later portions, so that as the knife rotates it enters progressively further into the space, thereby slicing across the filaments held in the slot, finally severing them completely.

In its simplest form the knife, as described above, is a piece of strip steel, but any other cutting surface may be employed, for instance the knife blade and the former may be made as one unit.

While the bend of the blade will not usually exceed 360, and is preferably 180, it is possible that to cut thick bundles of filaments such a long cutting surface will be required that a bend of more than 360 will be necessary. It will be appreciated that the length of the blade must be such that the speed at which it rotates enables it to pass through each space and not contact the projections.

The method of feeding the filaments to the knife may be any of those known in the art, but a preferred method comprises the use of a wheel with symmetrically spaced radial spaces, the filaments being held in contact with the periphery of the wheel, as shown in the accompanying drawings.

The width of each space at the cutting point should be as narrow as possible. Using a wheel it is sometimes necessary to expand the space as it penetrates into the wheel to allow for the change in relative angular position of the knife blade and the space walls, caused during the rotation of the wheel and blade.

It is, of course, not necessary to cut in every space and thus the one feeding means may be used to supply short filament lengths of different sizes, e. g. by missing alternate spaces and thereby cutting lengths twice the length obtained by using every space.

The filaments must be held firmly in contact with the projections on the feeding means both before and after the cutting point, to prevent the filaments slipping. This may be done in a variety of ways. Apart from the specific method already described with reference to the drawings any modification of this method or any other known method of gripping filaments may be used which does not interfere with the action of the knife.

To prevent damage to the filaments and to prevent them slipping, particularly during cutting, it is preferred that the surface on which they are held is resilient and, if possible, that they should be held in a groove. Thus using the preferred wheel the periphery at those points where the filaments are gripped should preferably be made of rubber or rubber-like material lying in the groove.

The apparatus of the present invention is simple in construction. The main advantages are that the knife cuts with a slicing action rather than a chopping action and that the blade, which is simply a fiat piece of steel, can readily be removed for resharpening. These qualities make the process particularly suitable for cutting tough artificial filaments, such as those of the synthetic linear poiyamides or highly polymerised polymethylene terephthalates, into short lengths, e. g. for use as staple fibre or brush bristles.

I claim:

1. Apparatus for cutting continuous filaments into short lengths comprising a wheel, a plurality of filament confining projections extending radially from said wheel, a cutting member mounted for rotation in a plane substantially tangent to but spaced slightly from the periphery of said wheel, said cutting member having an edge section shaped in spiral form relative to the rotational axis thereof, and an elongated knife blade detachably aifixed to the spiral edge section of said cutting member and extend-1 ing toward said wheel, said knife blade bein arranged to pass between said projections and out said filaments.

2. Apparatus according to claim 1, wherein said knife blade is tapered along its length whereby in cutting said filaments it penetrates progressively between said projections.

3. Apparatus according to claim 1, wherein said cutting member comprises a plurality of edge sections shaped in spiral form relative to the rotational axis thereof, and an elongated knife blade detachably amxed to each of said spiral edge sections and extending toward the wheel.

4. Apparatus for cutting continuous filaments into short lengths comprising a wheel, a plurality of filament confining projections extending radially from said wheel, said projections being arranged in laterally spaced pairs separatedfrom adjoining pairs by intervening spaces, a cutting member mounted for rotation in a plane substantially tangent to but spaced slightly from the periphery of said wheel, said cutting member having an edge section shaped in spiral form relative to the rotational axis thereof, and an elongated knife blade detachably afiixed to the;

spiral edge section or said cutting member and extending toward said wheel, said knife blade being arranged to enter said intervening spaces and. out said filaments, the point of contact of said knife blade and said filaments travelling with said filaments throughout each cutting op eration of the knife blade.

5. Apparatus according to claim 4, including a second wheel disposed adjacent said first named wheel with axis angulated slightly with respect to the axis of said first wheel, and a plurality of fingers extending from said second wheel substantially parallel to the axis thereof,

said second wheel being disposed to efiect engagement of its fingers with the projection pairs of said first Wheel in the vicinity of said cutting member.

RAYMOND HOLDEN SPEAKMAN.

References Cited in the file of this patent UNITED STATES PATENTS 10 Number Name Date 1,280,753 Juengst Oct. 8, 1918 2,205,036 Hamel June 18, 1940 

